It is known to fabricate structural parts for building walls from concrete using modular stay-in-place forms. Examples of such modular stay in place forms include those described in US patent publication No. 2005/0016103 (Piccone) and PCT publication No. WO96/07799 (Sterling). A representative drawing depicting a partial form 28 according to one prior art system is shown in top plan view in FIG. 1. Form 28 includes a plurality of wall panels 30 (e.g. 30A, 30B, 30C, 30D), each of which has an inwardly facing surface 31A and an outwardly facing surface 31B. Each of panels 30 includes a terminal male T-connector component 34 at one of its transverse, longitudinally-extending edges (longitudinal being the direction into and out of the FIG. 1 page) and a terminal female C-connector component 32 at its opposing longitudinal edge. Male T-connector components 34 slide longitudinally into the receptacles of female C-connector components 32 to join edge-adjacent panels 30 to form a pair of substantially parallel wall segments (generally indicated at 27, 29). Depending on the needs for particular wall segments 27, 29, different panels 30 may have different transverse dimensions. For example, comparing panels 30A and 30B, it can be seen that panel 30A has approximately ¼ of the transverse length of panel 30B.
Form 28 includes support panels 36 which extend between, and connect to each of, wall segments 27, 29 at transversely spaced apart locations. Support panels 36 include male T-connector components 42 slidably received in the receptacles of female C-connector components 38 which extend inwardly from inwardly facing surfaces 31A or from female C-connector components 32. Form 28 comprises tensioning panels 40 which extend between panels 30 and support panels 36 at various locations within form 28. Tensioning panels 40 include male T-connector components 46 received in the receptacles of female C-connector components 38.
In use, form 28 is assembled by slidable connection of the various male T-connector components 34, 42, 46 in the receptacles of the various female C-connectors 32, 38. Liquid concrete is then introduced into form 28 between wall segments 27, 29. The concrete flows through apertures (not shown) in support panels 36 and tensioning panels 40 to fill the interior of form 28 (i.e. between wall segments 27, 29). When the concrete solidifies, the concrete (together with form 28) provide a structural component (e.g. a wall) for a building or other structure.
A problem with prior art systems is referred to colloquially as “unzipping”. Unzipping refers to the separation of connector components from one another due to the weight and/or outward pressure generated by liquid concrete when it is introduced into form 28. By way of example, unzipping may occur at connector components 32, 34 between panels 30. FIG. 2 schematically depicts the unzipping of a prior art connection 50 between male T-connector component 34 and corresponding female C-connector component 32 at the edges of a pair of edge-adjacent panels 30. The concrete (not explicitly shown) on the inside 51 of connection 50 exerts outward forces on panels 50 (as shown at arrows 52, 54). These outward forces tend to cause deformation of the connector components 32, 34. In the FIG. 2 example, connector components 32, 34 may exhibit deformation in the region of reference numerals 56, 58, 60, 62, 64, 68. This deformation of connector components 32, 34 may be referred to as unzipping.
Unzipping of connector components can lead to a number of problems. In addition to the unattractive appearance of unzipped connector components, unzipping can lead to separation of male connector components 34 from female connector components 32. Form 28 may be unable to hold the liquid concrete, resulting in a loss of liquid concrete and potentially require significant repair procedures. To help counteract the unzipping problem, prior art systems typically incorporate support panels 36 and tensioning panels 40, as described above. However, support panels 36 and tensioning panels 40 represent a relatively large amount of material (typically plastic) which can increase the overall cost of form 28. Furthermore, support panels 36 and tensioning panels do not completely eliminate the unzipping problem. Notwithstanding the presence of support panels 36 and tensioning panels 40, in cases where male connector components 34 do not separate completely from female connector components 32, unzipping of connector components 32, 34 may still lead to the formation of small spaces (e.g. space 70 of FIG. 2) between connector components 32, 34. Such spaces can be difficult to clean and can represent regions for the proliferation of bacteria or other contaminants and can thereby prevent or discourage the use of form 28 for particular applications, such as those associated with food and liquid storage or handling or other applications requiring sanitary conditions or the like. Such spaces can also permit the leakage of liquids and/or gasses between inside 51 and outside 53 of panels 30. Such leakage can prevent or discourage the use of form 28 for applications where form 28 is required to be impermeable to gases or liquids. Such leakage can also lead to unsanitary conditions on the inside of form 28.
There is a general desire to provide modular form components and connections therefor which overcome or at least ameliorate drawbacks with the prior art.